Assigbtor to pbessube



v L. C. MARSHALL.

PISTON PACKING.

APPLICATION HLEDAUG.25. 1919.

1,41 2,25 1 Patented Apr. 11, 1922,

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UNITE!) S'l'ri'il @EFIQG LEWIS C. MARSHLL, OF VJ'ALPOLE, Ie'fiS ACI-EUSETTS,

ASSIGNGR TO PRESSURE OF MASSACHUSETTS.

PISTON' PACKNG.

Application filed August 25, 1919.

To @ZZ @rtl-07a t may concert/t Be it novn that l", Lewis C. MARSHALL, citizen of the Unite-d States, and resident of lllalpole., in the county et' Norfolk and State ot liassachusetts, have invented neu7 and useful improvements in Piston Packings, ot which the following` is a specification. l

rhis invention relates to piston packings and vvhile adapted to the packing of pistons generally, it isespecially designed for the packing ot pistons ot internal combustion engines. ln such engines in operation the cylini'ler is cooled while the piston is hot and thel latter therefore expands more than the cylinder and must fit loosely Within the cylinder to avoid binding. In order` to maintain the high compression which is necessary the piston is provided with pack- .ing` rings which not only must it tightly against the cylinder Wall, but must make a tight joint with the groove of the piston Wit-hin which the rings are disposed. to prevent leakage underneath the piston rings.

The principal obj'ect ot the present invention is to provide a novel and improved metallic piston packing which shall accomplish these results and Which shall also be simple in construction and free from multiplicity or parts and complexityk oi construction.

In the accompanying` drawings which illustrate an embodiment of the invention;-

Figure l is a side elevation of the packing rings in place on a piston head;

Figure 2 is a sectional view of said packing' rings in place on a piston head;

igure 3 is an enlarged detail view in moss-section7 illustrating' the form of packing" rings shown in Figs. l and 2; and

Figure 4r is enlarged detail view in cross-section, illustrating a slight modifie( tion of the structure shown in Fig. 3.

Referring` to the drawings l represents the piston head of an engine which is adapted to reciprocate Within the bore of the cylinder 2. The piston head is provided with grooves 3 within whichA packings are positioned tor vforming gas tight lioint between the piston head and the cylinder Wall. Each packing; comprises a packing ring 4l o: grey cast iron or other suitable material preferably having an external diameter substantially equal to the diameter of the bore ot the cylinder 2. The ring l is divided at S eccation of Letters Patent.

Patented Apr-.'11, 1922.

Serial No. 319,751.

'le point V5 to enable it to be sprung y for ins rtion in the groove 3 and to expand against the cylinder trapezitorm in cross-section as y shown in Fig. 3. The upper faces 6 and 7 or the ring' are parallel to each other and at right angles to the outer peripheral face 8. The inner peripheral face 9 oit the ring t is beveled at a suitable angle to the outer face S.

Resting upon the lower Wall of the groove 3 is a second ring l() substantially L-shaped in cross-section, that is, composed of two flanges7 one a radially disposed base flange, and the other an upstanding flange at an acute angle to the base flange. Ring' l0 is preferably made ot erm cast iron but may lie made of other suitable material. ring is beveled upon its outer peripheral tace 11 to the same extent as the inner face 9 et packing,` ring el and is adapted to make a tiQht joint therewith, and is preferably so constructed as to have an initial tendency to expand outwardly against the packing ring although it' desired thistendency might he eliminated. The upper surface of the base tia-nge l2 constitutes a radial seat surface M upon which a spring steel :torcer or 'toller/'er ring` l5 is positioned in Contact with the inner beveled face of the flange i3 of the ring l0 at a point which is substantially opposite the mid-region of the beveled surface ll. By so positioning the lollov ring l2, its Xpansive force is thereby directed against the central region oit the packingring el, and the ring 4- is thereby urged more evenly against the Wall of the cylinder and the Wear is evenly distributed on its outer peripheral face. Furthermore any tendency of the ring' to twist is eliminated and the upper face 6 of the packing' ring is urged with an even bearing; agains the upper wall of the groove 3. rThe ring' 10 not only serves to position the tollovver ring Vl5 in a position opposite the central reg-ion of the packing ring 4, but se ves to otl'set any tendency of the packing ringg to twist in the piston groove and so seals the joint between the ring; L and the all et the piston groove 3.

, rings are assembled in the groove of the piston head in such position that the points of division or the rings break joint. iii/Then assembled in the groove of the piston head as shown in Figs. l, 2 and 3, the ring 4 lits against the cylinder bore and is urged into Contact therewith by the ring 10 which inturn is expanded by the spring follower ring 15. One component of the force exerted against the beveled face 9 of the packing ring 4 tends to expand the ring 4 and thereby effect a tight closure between the periphery of ring 4 and the cylinder Wall; while the other component of said force tends to thrust said packing ring bodily endwise with relation t0 the piston head 1 and thereby holds the face 6 in tight engagement with the upper wall of the groove 3. Thus the packing ring is maintained tight against loss of pressure both between the ring and the cylinder wall and underneath the ring between the ring and the piston head.

lower ring 15 as formed from steel wire having' both sides ground or drawn flat, it is to be understood that round steel wire or Wire of any other suitable form of spring wire might be used.

From the foregoing description it is apparent that I have provided a piston packing comprising three rings one of which is a packing ring, the rings being held in such positions relative to each other that the packing ring is urged radially and upwardly with no tendency to twist within the piston head groove and in consequence presents its packing surfaces squarely against the piston head and cylinder walls with which they are designed to engage, thereby sealing the piston head to the cylinder by a gas tight joint.

I claim:

1. In combination, a piston having an annular groove therein, and a packing in said groove comprising a packing ring having a beveled face,a second ring having two singularly disposed flanges intersecting substantially 1n the middle of the longitudinal dimension of the ring and forming an annular radialseat surface on the inner peripheral face of said ring, one of said flanges having a beveled outer peripheral face cooperating with the beveled face of said packing ring and an inner beveled face overhanging said seat surface, and aV spring follower ring supported upon said seat and adapted to urge said second ring outwardly against said packing ring whereby said packing ring is urged both in a radial direction and in an endwise direction on the piston against the upper wall` of said groove.

2. VIn combination, a piston having an annular groove therein, and a packing in said groove comprising a packing ring having a beveled inner face, a second ring having Vinner and outer iaces, said outer lface'cooperating with the beveled face of said packing ring, and a spring follower ring supported upon said seat and underlying the inner beveled face of said second flange, said follower ring being adapted to urge' said rings in a radial direction and said packing ring in a direction endwise o't the piston and against the upper wall ot said groove.

In combination, a piston having an annular groove with upper and lower walls therein, and a packing in said groove comprising a packing ring trapeziform in crosssection and of less width than the width of said groove, the inner peripheral face of said ring being beveled, a second ring having two angularly disposed flanges, one of said flanges providing an annular seat in a median plane of the groove and on the inner peripheral face of said ring and the other of said flanges having a beveled outer peripheral face cooperating with the beveled face of said packing ring, said second llange being of less radial depth than the first iiange, and a spring follower ring supported upon said s eat and underlying the inner surface of said second flange and adapted to urge said second ring against the lower wall of the groove and outwardly against said packing ring whereby said packing ring is urged both in a radial direction and in an endwise direction on the piston against the upper wall of said groove.

1 1. In combination, a piston having an annular groove therein, and a packing in said groove comprising a packing ring, the inner peripheral face oi' said ring being beveled, a second ring L-shaped in cross-section resting upon the lower wall of said groove, one flange of said second ring providing an internal annular seat and the other of said flanges having beveled inner and outer faces, said latter flange overhanging said first liange but being of' less radial extent, theY outer iace of said` latter flange cooperating with the beveled face or' said packing ring, and a(b spring follower ring supported upon said seat and engaging the inner beveled tace of said flange to hold the ring against the lower wall, and to urge said rings in a radial direction whereby said packing ring is urged in an endwise direction on the piston against the ripper wall of said groove.

Signed byv me at Boston, Massachusetts, this 4th day ofAugust 1919.

LEWIS C. MARSHALL. 

